President Donald Trump has asked Congress to give NASA an additional $1.6 billion in the coming year to jump start an effort to put humans on the moon by 2024 — but experts say the space agency will need billions more.

The additional money would help NASA develop a commercial lunar lander for humans three years earlier than planned, funnel more money into the Space Launch System rocket being built to take the Orion spacecraft to the moon and enable more robotic exploration of the moon's polar regions before a human mission.

"This is a small down payment of what will be a rather large amount," said Keith Cowing, editor of NASA Watch, a website devoted to space news. "At the end of the day, show me the money."

NASA has decided to name the latest moon effort "Artemis" — the sister of Apollo and goddess of the moon.

During a news conference Monday night, NASA Administrator Jim Bridenstine said the funding requests would only increase as the agency gets closer to the 2024 deadline, though he could not provide a number for how much the total project would cost.

"I would love to tell you that, and we're working through that diligently," he said. "We expect in future years it will be more."

'Sets us up for success'

Two months ago, the Trump administration directed NASA to put humans on the moon four years earlier than planned, in 2024 instead of 2028. But that directive did not come with a budget request to back it up.

In the days and weeks since, congressional leaders have grown increasingly impatient that the agency could not provide a plan for reaching the objective, especially after a Trump administration request for a half-billion-dollar cut in the NASA budget beginning Oct. 1. With the new request, Trump is now asking for $22.6 billion for the agency.

"This is a good amount that gets us out of the gate in a strong fashion and sets us up for success in the future," Bridenstine said. "This boost lets us move forward with design, development and exploration."

The plan would use technology and hardware already under development, including a mini-space station orbiting the moon, called the Lunar Orbital Platform-Gateway, and the Space Launch System rocket designed to launch the Orion spacecraft.

The goal is to fly two SLS-Orion missions — one without humans and another with crew aboard — prior to 2024. The mini space station would also be launched during that period. Then in 2024, the third SLS-Orion mission would rocket to the Gateway, where astronauts would board a lunar lander waiting to take them to the moon's surface.

But the plan is fraught with problems. The SLS, the largest rocket NASA has ever built, has suffered numerous setbacks since Boeing began building it in 2012. The rocket is the brainchild of President Barack Obama's administration and initially was scheduled to launch in 2017.

That, of course, didn't happen. And earlier this year, Boeing informed NASA that the SLS would not make the most recent launch date of June 2020. They'll need until 2021 instead.

Despite the problems, Bridenstine again stood behind the SLS rocket, which has cost NASA about $12 billion so far — saying on Monday it was necessary for the plan.

"The only way to get humans to the surface of the moon is on the SLS in the Orion crew capsule," he said. "It's an absolutely critical piece of the architecture."

Additional resources

The budget request from Trump would funnel another $651 million to SLS and Orion, as well as $1 billion so NASA can begin developing a commercial lunar lander for humans.

Also included in the request is $132 million for technologies that will support the advancement of lunar exploration, such as solar-electric propulsion, and $90 million to pay for more robotic exploration of the moon's polar regions before 2024.

Bridenstine did not know what federal programs might have been cut to allow for these increases, but no NASA programs were slashed to make this happen.

"That's above my pay grade," Bridenstine said. "As far as other programs or where the money is coming from, we have not been briefed."

Trump tweeted about the proposal increase Monday afternoon.

"Under my Administration, we are restoring @NASA to greatness and we are going back to the Moon, then Mars," Trump tweeted. "I am updating my budget to include an additional $1.6 billion so that we can return to Space in a BIG WAY!"

Alex Stuckey writes about NASA and the environment for the Houston Chronicle. You can reach her at alex.stuckey@chron.com or Twitter.com/alexdstuckey.

Alex Stuckey is an investigative reporter for the Chronicle. Stuckey won a Pulitzer Prize in 2017 for her work on a project examining the rampant mishandling of sexual assault reports at Utah colleges while working for The Salt Lake Tribune. She came to the Chronicle shortly thereafter to write about NASA, science and the environment.

Stuckey is an Investigative Reporters and Editors award winner and a Livingston Award Finalist. She has won a Sigma Delta Chi Award for Excellence in Public Service Journalism and a Frank A. Blethen Award for Local Accountability Reporting. She also has won a Society of Professional Journalists Don Baker Investigative Reporting Award.

An Ohio native, Stuckey has lived in five states since graduating from Ohio University’s E.W. Scripps School of Journalism in 2012. She loves yoga, reading and elephants. She shares a birthday with Ruth Bader Ginsburg (girl power!) and the late Alan Bean, fourth man to walk on the moon.